1. Field of the Invention
The invention concerns a jacket enclosing a lengthy body. More particularly, the invention concerns a braided jacket enclosing a load-bearing, lengthy body, for example ropes and mooring equipment.
2. Description of the Related Art
Mooring equipment is subjected to large loads. Besides being load-bearing and exposed to tensile forces, the surface of the mooring equipment is exposed to filing, rubbing, strikes and cuts. Particles, such as sand, may penetrate into the mooring equipment if, for example, it is attached to an anchor lying on a seabed, and the particles may cause internal wear and tear. Mooring equipment is also exposed to buckling.
It is known that lengthy bodies, such as ropes, mooring equipment, electric cables, hoses and pipes, at least at an end portion thereof, may be provided with a protective jacket. This jacket may be braided, as shown in e.g. patent publications U.S. Pat. No. 4,312,260; U.S. Pat. No. 4,640,178 and U.S. Pat. No. 6,099,961. For braiding of the protective jacket, it is known to use braid elements of laid fibres. From patent publication NO 314459/WO03054291, it is known that the braid elements in the protective jacket is comprised of woven ribbons.
Patent publication EP 1700948 describes a braided protective jacket for a rope. The protective jacket comprises a plurality of braid elements comprised of threads. The patent publication is silent about the construction of the threads in the braid elements. Further, the protective jacket comprises a plurality of reinforcement threads incorporated in the braiding. The patent publication provides no clear disclosure of the manner in which this is done, but the reinforcement threads are not a part of the braid elements.
Patent publication WO 2005/019525 describes a braided, load-bearing rope provided with a lengthy core. The core increases the rope's resistance against squeezing, but the core has no function as a load-bearing element. The load-bearing rope is not surrounded by any protective jacket.
A number of requirements exist with respect to a protective jacket. A protective jacket together with a piece of mooring equipment is used as an example. The protective jacket should be pliable and such that the stiffness or bend radius of the mooring equipment does not increase. The protective jacket should be tight, whereby foreign bodies do not penetrate into the mooring equipment. The protective jacket should exhibit good resistance against filing and rubbing. During use, the mooring equipment may be exposed to a cut from a sharp object. The protective jacket should be constructed in such a manner that the protective jacket provides protection against the cut from most possible angles at which the cut may be directed towards the mooring equipment, and such that the protective jacket does not open. A protective jacket should also be allowed to be provided with reinforcements against cuts. A protective jacket should also be allowed to be provided with a streamline coating, which is termed fairing in the art. Fairing is comprised of protruding, cut threads so as to form floss. This gives the mooring equipment improved properties when pulled through the water.
It is generally known in the art that a number of monofilament fibres are laid in a first direction, for example to the left, to produce a so-called yarn. By so doing, the yarn produced is a twisted multifilament. Several yarns are laid in a second direction to produce a so-called composite bundle or strand. Three strands are laid in the first direction to produce a so-called hawser, then forming a three-strand laid hawser. Several hawsers may be laid in the second direction to produce a cable. It is also known that a four-strand laid hawser is comprised of four strands, in which one strand forms a core, a so-called calf. Further, it is known that e.g. hawsers may be comprised of more than four strands. The above does not constitute a complete disclosure of this field in the art. Examples are also known in which the lay-direction deviates from what is described herein.
A disadvantage of laid ropes is that they may twist during loading. Ropes produced via braiding of yarn, strand or hawser will not twist.
Synthetic textile fibres are produced as monofilaments being, in principle, of endless length. Hereinafter, use of synthetic textile fibres is described, but the skilled person will know how the terms may be used with respect to natural fibres. A textile element is comprised of one or more textile fibres.
Hereinafter, a thread will be used as a common term for one lengthy textile element. In its simplest form, a thread is comprised of one monofilament. Further, a thread may be comprised of two or more monofilaments lying side by side and without being twisted about each other. This will be termed a bundle. Further, a thread may be comprised of two or more monofilaments twisted about each other into, for example, a yarn. Further, a thread may be comprised of a strand, a hawser or a cable, as described above. Further, a thread may be comprised of braided textile elements comprised of a monofilament, a bundle, a yarn, a strand, a hawser or a cable. A thread is further characterized in that the thread exhibits a substantially circular cross-section.
Weaving is characterized in that a group of threads, so-called warp or warp thread, is perpendicular to another group of threads, so-called woof or weft. Braiding is characterized in that the threads are functionally equivalent and are conveyed forward, whilst being cross-laid into a zigzag-pattern, below or above the other threads. A first half of the threads are conveyed spiralling forward in one direction and a second half of the threads are conveyed spiralling forward in a second direction.
The term ribbon implies a lengthy element comprised of a plurality of threads, wherein the threads may be formed in various ways, and wherein the threads may be comprised of various materials. A ribbon may be formed via weaving or via braiding and such that the ribbon in a first direction, height/thickness, is substantially shorter than in a second direction, width, wherein the first direction is perpendicular to the longitudinal direction of the ribbon, and the second direction is perpendicular both to the longitudinal direction of the ribbon and to the first direction. As such, and as an example, the ratio between the first direction, the height, and the second direction, the width, may be 1:3; 1:4; 1:5; 1:10; 1:20. The skilled person will know that this ratio varies with the number of threads in a warp, or the number of threads in a braiding.
A braided ribbon may be produced via braiding of, for example, 12 threads, wherein 6 threads lie side by side in a first direction and 6 threads lie side by side in a second direction. The threads cross each other in particular patterns, such as e.g. over 2-under 2, or over 1-under 1. Other patterns are also available. When a thread, which lies in a first direction, is braided outwards to the edge of the ribbon, it is bent and is braided inwards along the ribbon in the second direction. The minimum number of threads in a ribbon is 3 threads. Ribbons having 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 32, 64 or 128 threads are known. It is obvious in the art to produce ribbons having a number of threads deviating from this, and it is known that the complexity of the braiding machines increases with the number of threads to be braided into a ribbon.
The object of the invention is to remedy or to reduce at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art.